13.Bg5 Qd7 {everything looks normal upto move 13. but 13 ...Qd7 looks like a mistake, may better to block with the bishop with Be7.}
14.Rad1 Bg7 15.d5 Ne7 16.Qd2 a6 17.Bh6 Bxh6 {17 ... Bxh6? I'm pretty sure this is a bad move because of the queen recapture and Ng5}
18.Qxh6 f5 19.Ng5 Nxd5 20.Bxd5+ {Bxd5+ seals the deal with a great interference move 21 Bf7 and even after the queen gives herself up there is no stopping the mate after} Kh8 21.Bf7 1-0

[Event "Casual Correspondence game"]
[Site "https://lichess.org/bzfkyi4J"]
[Date "2018.04.07"]
[Round "-"]
[White "ealtin"]
[Black "dendiz"]
[Result "0-1"]
[UTCDate "2018.04.07"]
[UTCTime "20:10:54"]
[WhiteElo "1500"]
[BlackElo "1500"]
[Variant "Standard"]
[TimeControl "-"]
[ECO "D02"]
[Opening "Queen's Pawn Game: Symmetrical Variation"]
[Termination "Normal"]
[Annotator "lichess.org"]
Nf3 d5
d4 Nf6 { D02 Queen's Pawn Game: Symmetrical Variation }
Nc3 a6 {A questionable move by black, should actually continue with development. The reason I played this was I thinking of my queen on c7 but it's premature.}
Bf4 Bg4 5. Qd3 {A hint at queen side castling by white. } e6
e4 {looks like a mistake after dx4 Nxe4 Bf5 white is a pin, but has Nxf3+ to wiggle out of it.} dxe4 7. Nxe4 Nbd7 8. d5 Nxe4
Qxe4 Nf6 10. Qa4+ {after this move I took some time on how to block the check. Nd7 or Qd7 leads to an equalish position after the piece exchanges and looks boring.} b5
Qa5 {here I took some time too. The sensible moves looks like Nxd5 but the more adventurous move was to take with to Queen and establish a central dominance on the position.
I thought about 12 Qxc7 Bxf3 13. gxf3 Qxf3 attacks to took on h1 and protects my rook on a8. I didn't see any checks for black that would be threatening. But still it is risk position without
the black king uncastled} Qxd5
Rd1 {this was a blunder by white. allowing the queen to give the check and the combination to win to queen.} Qe4+ 13. Be2 Bb4+ 14. Qxb4 Qxb4+
c3 Qxf4 16. O-O Bxf3
Bxf3 Ng4 18. Rd4 Qxh2# { Black wins by checkmate. } 0-1